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SubjectRe: [PATCH 4/4] KVM/VMX: Fold handle_interrupt_nmi_irqoff() into its solo caller
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On 30/04/21 11:03, Thomas Gleixner wrote:
> Lai,
>
> On Tue, Apr 27 2021 at 07:09, Lai Jiangshan wrote:
>> u32 intr_info = vmx_get_intr_info(&vmx->vcpu);
>> @@ -6427,12 +6417,19 @@ static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx)
>> static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu)
>> {
>> u32 intr_info = vmx_get_intr_info(vcpu);
>> + unsigned int vector;
>> + gate_desc *desc;
>>
>> if (WARN_ONCE(!is_external_intr(intr_info),
>> "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info))
>> return;
>>
>> - handle_interrupt_nmi_irqoff(vcpu, intr_info);
>> + vector = intr_info & INTR_INFO_VECTOR_MASK;
>> + desc = (gate_desc *)host_idt_base + vector;
>> +
>> + kvm_before_interrupt(vcpu);
>> + vmx_do_interrupt_nmi_irqoff(gate_offset(desc));
>> + kvm_after_interrupt(vcpu);
>
> So the previous patch does:
>
> + kvm_before_interrupt(&vmx->vcpu);
> + vmx_do_interrupt_nmi_irqoff((unsigned long)asm_noist_exc_nmi);
> + kvm_after_interrupt(&vmx->vcpu);
>
> What is this idt gate descriptor dance for in this code?

NMIs are sent through a different vmexit code (the same one as
exceptions). This one is for interrupts.

Paolo

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